PARIS — The brazen robbery had all the elements of a Hollywood thriller: a commando-style ambush, a suitcase stuffed with cash, mysterious stolen documents, and an anonymous member of the Saudi royal family heading to the airport.

It was a quiet Sunday evening, sometime after 5 p.m., when the Saudi royal, whom the authorities would not identify, left the Four Seasons Hotel George V, one of the French capital’s most sumptuous hotels, where a “Première Room” costs nearly $2,200 a night. He left for Le Bourget Airport north of Paris, where captains of industry and visiting royalty park their private jets.

The Saudi royal was traveling as Saudi royalty often do, in a convoy, led by a Mercedes minivan. Inside one of the dozen cars was a suitcase stuffed with 250,000 euros, about $335,000.

No one has said why the Saudi royal was traveling with so much cash, though wealthy Arabs have been known to pay in cash while shopping at vaunted boutiques in Paris such as Cartier or Valentino.

But clearly, the authorities said, someone knew the money was there. Eight masked gunmen driving in two BMWs swooped down on the convoy sometime between 5 and 8 p.m., the police said, and forced the lead car to stop.

Within seconds, and without firing a shot, they drove away with the suitcase filled with cash and, according to French media reports, official embassy documents.

“The assailants blocked the car with two vehicles and asked the occupiers to get out of the car,” said Denis Fauriat, a spokesman for the prosecutor’s office in Paris. “Then, they took the car and drove away. It took them a few dozen seconds to do that.” He said that a member of the Saudi royal family was part of the convoy.

Mr. Fauriat said he believed that the attack was a robbery led by “criminals who seemed to know that there was money to steal, and eventually knew in which car they would find it.”

The robbery took place near Porte de la Chapelle, prosecutors said, a working class, immigrant neighborhood in the northern periphery of the French capital.

The French news media reported that the thieves who commandeered the Mercedes eventually released the driver, an official and a bodyguard on the side of the road. The police initially said the thieves wielded Kalashnikov rifles, but later said they had handguns. The Mercedes was later found abandoned and burned, the police said, its charred remains discovered near a wooded area, along with one of the gang’s burned BMWs.

Prosecutors are investigating whether the robbery was an inside job, as the gunmen appeared to know the convoy’s route. The French police have opened an investigation into “armed theft by an organized gang,” but there have been no arrests.

“The robbers were experienced, well organized,” said Nicolas Comte, a police officer and secretary general of Unité SGP Force Ouvrière, a leading police union. “They did it with self-control and equipment, without committing any mistake. We can imagine that they knew that a large amount of money was being carried, and that perhaps people in the convoy knew some of the robbers.”

The police did not reveal the names of the victims. In a statement published on the S.P.A., the state news agency of Saudi Arabia, the Saudi Embassy in Paris said that the stolen car was a Mercedes Viano with German plates and rented by a Saudi citizen, “who was heading for the airport with his luggage.”

“On the way, the driver was forced to get out the car,” the statement said. “The luggage and car were stolen.”

On the official Facebook page of the Saudi Ministry of Foreign Affairs, a statement was also issued denying reports by the French police and news media that a car belonging to the Saudi Embassy had been attacked on the way to the airport, “where money and sensitive documents were stolen.” Such reports, the statement said, “are not true at all.” The statement also quoted one delivered by the embassy saying that it was cooperating with the French authorities.

The crime fit the pattern of other recent attacks in the French capital, law enforcement officials said, and Mr. Comte, the police officer, said the threat of violence and the element of surprise suggested that its perpetrators could be from Eastern Europe or the Balkans. In recent years, criminals from the former Yugoslavia, including globe-hopping jewel thieves known as the Pink Panthers, have snatched jewels worth hundreds of millions of dollars, from Dubai to Geneva to Paris, in swift “snatch and grab” attacks that usually take no more than three minutes.

He said the thieves could also be homegrown criminals.

As tourists flood the French capital, law enforcement officials said, criminals were targeting wealthy foreign shoppers, including women, in swift and violent surprise attacks. Mr. Comte, the police officer, said that the carjackers typically rode motorcycles with false license plates and preyed on wealthy female tourists in luxury cars, diplomatic vehicles, and vehicles carrying well-dressed shoppers, including taxis.

While the audaciousness of the assault on the Saudi convoy captured the imaginations of Parisians returning from their summer holidays, it also was likely to fan fears among visiting dignitaries in Paris after a series of hijackings in the capital.

In July, more than a dozen people performed several similar hijackings, the newspaper Le Figaro reported, obstructing a road leading to the A6 motorway.

According to French news media reports, in July of last year robbers disguised as the police targeted a senior Saudi official from the ministry of sports close to Le Bourget airport after he had arrived in Paris, and then fled with about $267,000 in cash.

In February 2010, the daughter of the mayor of Kiev, who was riding in a luxury car on the A1 highway, was attacked in a similar fashion, Le Figaro reported, with the robbers snatching about $6 million worth of jewelry.

Some of the legions of upwardly mobile Chinese tourists visiting Paris have also been targeted in high-profile muggings and robberies, prompting the authorities in China to consider sending law enforcement officials to the French capital.

The historic Place Vendôme neighborhood in Paris has also been the scene of a series of spectacular jewelry heists in recent months, including a break-in at the city’s cathedral of cool, Colette, in March, when two thieves armed with a pump-action gun and an ax stormed the shop’s entrance and fled with more than $800,000 worth of deluxe watches.

A version of this article appears in print on , on Page A6 of the New York edition with the headline: Saudi Is Robbed in Paris, Quickly and Efficiently. Order Reprints | Today’s Paper | Subscribe